Background & Aims Limited data exist regarding the actual risk of developing advanced adenomas and cancer following polypectomy or the factors that determine risk. Methods We pooled individual data from 8 prospective studies comprising 9167 men and women aged 22 to 80 with previously-resected colorectal adenomas to quantify their risk of developing subsequent advanced adenoma or cancer as well as identify factors associated with development of advanced colorectal neoplasms during surveillance. Results During a median follow-up of 47.2 months, advanced colorectal neoplasia was diagnosed in 1082 (11.8%) of the patients, 58 of whom (0.6%) had invasive cancer. Risk of a metachronous advanced adenoma was higher among patients with 5 or more baseline adenomas (24.1%; SE=2.2) and those with an adenoma 20 mm in size or greater (19.3%; SE=1.5). Risk factor patterns were similar for advanced adenomas and invasive cancer. In multivariate analyses, older age (P <0.0001 for trend) and male sex (odds ratio [OR], 1.40; 95% confidence interval [CI] 1.19–1.65) were significantly associated with increased risk of metachronous advanced neoplasia, as were the number and size of prior adenomas (P <0.0001 for trend), the presence of villous features (OR, 1.28; 95% CI 1.07–1.52), and proximal location (OR, 1.68; 95% CI 1.43–1.98). High-grade dysplasia was not independently associated with metachronous advanced neoplasia after adjustment for other adenoma characteristics. Conclusions Occurrence of advanced colorectal neoplasia is common following polypectomy. Factors that are most strongly associated with risk of advanced neoplasia are patient age and the number and size of prior adenomas.

effects of treatment overall and within subgroups of baseline prostate-specific antigen (PSA) and plasma selenium concentrations were examined using incidence rate ratios and Cox proportional hazards models. RESULTSSS continued to significantly reduce the overall incidence (relative risk and 95% confidence interval) of prostate cancer (0.51, 0.29-0.87). The protective effect of SS appeared to be confined to those with a baseline PSA level of £ 4 ng/mL (0.35, 0.13-0.87), although the interaction of baseline PSA and treatment was not statistically significant. Participants with baseline plasma selenium concentrations only in the lowest two tertiles (< 123.2 ng/mL) had significant reductions in prostate cancer incidence. A significant interaction between baseline plasma selenium and treatment was detected. CONCLUSIONTo the end of the blinded treatment the NPC trial continued to show a significant protective effect of SS on the overall incidence of prostate cancer, although the effect was restricted to those with lower baseline PSA and plasma selenium concentrations.

The increased risk of colorectal cancer associated with a high BMI might be largely restricted to tumors that display the more common MS-stable phenotype, suggesting further that colorectal cancer etiology differs by tumor MSI status.